Current and historical procedures for treatment of colon and rectal cancer generally have been based upon the natural history of tumor spread, and thence, upon operative and non-operative options available to the practitioner. Operative options generally have looked to the physical identification and surgical resection of tumor. A variety of techniques have been brought to bear in the art with the purpose of aiding the surgeon in detecting and localizing neoplastic tissue as part of this surgical procedure. ("Neoplastic tissue," for the present purposes, often is referred to as cancerous tissue, though malignant tumor and malignant tumor cells also are found in the terminology of the art. The term "neoplastic tissue" includes all of these.) A substantial amount of the effort which has been expended in seeking to aid the surgeon in the process of locating neoplastic tissue has been concerned with the utilization of radiolabeled antibody. For example, one technique includes the scintillation scanning of patients who have been injected with relatively high energy, e.g. .sup.131 I labeled antibodies. Such photoscanning or scintillation scanning produces scintigrams which are difficult to interpret because of blood pool background radioactivity. Computer subtraction of radioactive blood pool agents and the use of two labeled antibodies (one specific for the tumor and one non-specific) have been attempted in an effort to enhance imaging. Nevertheless, such techniques have been found to provide little, if any, useful information to the surgeon, especially over and above the CAT scan, magnetic resonance imaging, and like traditional techniques. Typically, large tumor is readily located by the surgeon by visualization at the operating theater, and, in particular, through palpation, i.e. the feel of tumor as opposed to that of normal tissue. To achieve operative success, however, it is necessary for the surgeon to somehow locate "occult" tumor, i.e. tumor which cannot be found by the conventional surgical procedures of sight and feel. Failure to locate and remove such occult tumor generally will result in the continued growth of cancer in the patient, a condition often referred to as "recurrent" cancer. In general, conventional diagnostic techniques as, for example, use of the classic gamma camera and the like, fail to find or locate occult tumor. As tumor sites become smaller, the radionucleide concentrations at a given site will tend to be lost, from an imaging standpoint, in the background where blood pool radiation necessarily is present in the patient.
In 1984, Martin, M. D., and Thurston, Ph. D., introduced a much improved method for locating, differentiating, and removing neoplasms. Such technique uses a radiolabeled antibody and a portable radiation detection probe which the surgeon may use intraoperatively in order to detect sites of radioactivity. Because of the proximity of the detection probe to the labeled antibody, the faint radiation emanating from occult sites becomes detectable, for example, in part because of the inherent application of the approximate inverse square law of radiation propagation. The procedure now is known as radioimmunoguided surgery (RIGS.RTM.) (RIGS being a registered trademark of Neoprobe Corporation of Dublin, Ohio). The RIGS system for surgery additionally is successful because of a recognition that tumor detection should be delayed until the blood pool background of the circulating radiolabeled antibody has had an opportunity to be cleared from the body. As a consequence, the photon emissions or radiation emitted at minute tumors compared to surrounding tissue becomes detectable in view of the proximity of the probe device to it. Fortuitously, the radiolabeled antibody is capable of remaining bound to or associated with neoplastic tissue for extended periods of time with the radio tag still bound thereto. Moreover, even though the accretion of radioactivity at the tumor site decreases over time, the blood pool background and surrounding tissue (relative to the tumor sites) decrease at a much greater rate so that the radioactive sites can be determined readily utilizing a hand-held probe positioned in close proximity with the tissue under investigation. The seminal patent concerned with the RIGS procedure is U.S. Pat. No. 4,782,840 by Martin and Thurston, entitled "Method for Locating, Differentiating, and Removing Neoplasms," issued Nov. 8, 1988, and assigned in common herewith, the disclosure of which is expressly incorporated herein by reference.
The important advances achieved through radioimmunoguided-surgery have been reported. See in this regard, the following publications:
(1) "Radioimmunoguided Surgery System Improves Survival for Patients with Recurrent Colorectal cancer" Bertsch et al. Surgery 1995; 118: 634-639. PA1 (2) "Radioimmunoguided Surgery in Primary Colorectal Carcinoma: An Intraoperative Prognostic Tool and Adjuvant to Traditional Staging," Arnold, et al. American J. Surg. 1995; 179: 315-318. PA1 (3) "The Significance of Intraoperative Periportal Lymph Node Metastasis Identification in Patients with Colorectal Carcinoma," Schneebaum, et al. Cancer 1995; 75: 2809-2817. PA1 (4) "Identification of Occult Micrometastases in Pericolic Lymph Nodes of Dukes' B Colorectal Cancer Patients Using Monoclonal Antibodies against Cytokeratin and CC49," Greenson, et al. Cancer 1994; 73: 563-569. PA1 (5) "Intraoperative Detection of Occult Colon Cancer Micrometastases Using .sup.125 I-Radiolabeled Monoclonal Antibody CC49," Cote, et al., Cancer 1996; 77: 613-620. PA1 U.S. Pat. No. 4,801,803 by Denen, Thurston, and Ramsey, entitled "Detector and Localizer for Low Energy Radiation Emissions," issued Jan. 31, 1989. PA1 U.S. Pat. No. 4,893,013 by Denen, Thurston, and Ramsey, entitled "Detector and Localizer for Low Energy Radiation Emissions," issued Jan. 9, 1990. PA1 U.S. Pat. No. 5,070,878 by Denen, entitled "Detector and Localizer for Low Energy Radiation Emissions," issued Dec. 10, 1991. PA1 U.S. Pat. No. 5,151,598 by Denen, entitled "Detector and Localizer for Low Energy Radiation Emissions," issued Sep. 29, 1992.
The radioimmunoguided surgical system instrumentation is comprised generally of two basic components, a hand-held probe as described above, which is in electrical communication via a flexible cable with a control console. This control console is located within the operating room facility but out of the sterile field, while the hand-held probe and forward portions of its associated cable are located within that field. The hand-held radiation detecting probe is relatively small and performs in conjunction with a cadmium zinc telluride detector or crystal.
The hand-held probe and preamplification electronics mounted within it in support of the cadmium zinc telluride crystal have been the subject of extensive scientific development. Cadmium zinc telluride crystals are somewhat fragile and exhibit piezoelectric properties which, without rigorous accommodation, will produce deleterious noise phenomena and the like. Further, the crystal and its operatively associated preamplification function are called upon to detect necessarily very faint radiation. In this regard, only a very small amount of radioactive locator will be associated with minute, occult tumor. Thus, radiation emission count rates measured with the RIGS system are relatively low. A resultant operational criteria then requires a crystal geometry of adequately large surface area and a complementing preamplification function exhibiting the equivalent of an extremely high signal gain. Research activity in meeting the above operational criteria is reflected in the following U.S. Patents.
To derive data representing the presence or absence of occult tumor, a microprocessor-driven complex system of analysis continuously works to statistically evaluate validated counts or gamma strikes to aurally apprise the surgeon of the presence or absence of occult neoplastic tissue. An algorithm under which the noted evaluation takes place is described in U.S. Pat. No. 4,889,991 by Ramsey and Thurston, entitled "Gamma Radiation Detector with Enhanced Signal Treatment," issued Dec. 26, 1989.
The RIGS system, not only having demonstrated its value in locating occult neoplastic tissue, also substantially aids the surgeon in determining the proper staging of the patient in accordance with the extent and severity of the disease. Such staging aids in determining the appropriate post-surgical treatment of patients. In this regard, an effective staging technique utilizing the RIGS system has been described wherein an R Number is determined in accordance with the formula: EQU R Number=(n.sub.1.times.E.sub.1).sub.1 +(n.sub.2.times.E.sub.2).sub.2 +(n.sub.3.times.E.sub.3).sub.3 +(n.sub.4.times.E.sub.4).sub.4
wherein each subscript 1-4 represents an anatomic zone, staging of the patient being based upon the R Number determination. See generally, Martin, Jr., U.S. Pat. No. 5,482,040, entitled "Biostaging of Adenocarcinomas Utilizing Radiolabeled Tumor-Associated Glycoprotein Antibodies," issued Jan. 9, 1996.
For many procedures, laparoscopic surgery (minimal access surgery) has become a desired alternative to traditional open surgery procedures. Particularly with the development of video-based visual systems, laparoscopic surgical techniques have been employed with more complicated gastrointestinal procedures. Such procedures look to savings in total health care costs as a result of shorter hospital stays and a more rapid patient return to normal activity. However, these procedures have required the development of instrumentation and techniques supplanting conventional three-dimensional viewing and tactile feedback to the surgeon.
In typical laparoscopic procedures, "space" for visualization by the surgeon via a video system, as well as for maneuvering laparoscopic instruments, is carried out in conjunction with a filling of the peritoneal cavity with a gas that distends the abdominal wall and provides an area for light and manipulation. This process is termed "pneumoperitoneum." Carbon dioxide currently is the standard gas used for pneumoperitoneum. Pneumoperitoneum typically is carried out utilizing an instrument referred to as an insufflator.
Laparoscopic surgical procedures generally feature the establishment of one or more portals of entry into the abdominal cavity. Mechanisms for inserting and removing various instruments through these portals without loss of pneumoperitoneum are necessary. These ports are established by the insertion of a trochar tip through the skin of the patient in conjunction with a port defining cannula or sheath. The trochar is inserted through the lumen of the cannula as an obturator. Typically the cannulas have an elastic valve to permit the introduction of instruments into the abdomen and prevent gas from escaping. Conventionally, the size of the cannula sleeve is 1 mm larger in diameter than the corresponding instrument that will traverse it. Diameters for such instruments may reach, for example, 15 mm, however, the surgical community prefers that the diameters of the instrument remain as small as possible.
The RIGS system has been introduced to laparoscopic surgery in connection with the surgical treatment of colorectal surgery. In a seminal patent concerning a laparoscopic probe instrument for carrying out the RIGS surgical system, the importance of a "side-looking" mounting of the cadmium telluride crystal is described. By utilizing such a crystal mounting, not only is the surgical procedure facilitated, but a crystal of adequate surface area may be used while the important diameter of the tubular-shaped instrument is maintained at a minimum value. See in this regard, U.S. Pat. No. 5,429,133 by Thurston and Slifko, entitled "Radiation Responsive Laparoscopic Instrument," issued Jul. 4, 1995. A diagnostic method for determining the treatment modality for neoplastic tissue within the peritoneal cavity of a patient utilizing a RIGS-based laparoscopic instrument is described in U.S. Pat. No. 5,383,456, by Arnold and Thurston, entitled "Radiation-Based Laparoscopic Method for Determining Treatment Modality," issued Jan. 24, 1995.
Developmental investigation of cadmium-telluride detector based probes has grown apace. Efforts looking to electrical noise phenomena avoidance have continued. Such endeavors have looked to noise sources and their accommodation. For example, scientific investigations now have revealed that probe designs should address a variety of noise inducing mechanisms accounting for the conversion of mechanical vibration to electrical pulses. These include the piezoelectric effect, the triboelectric effect and variations in capacitance between conducting surfaces. Prospective probe designs should remain amenable to practical manufacturing practices, as well as repairability features. In the latter regard, in their intraoperative environment of use, these very delicate instruments may be dropped or otherwise mishandled. In view of the continuing relatively higher cost of these instruments, such repair is of interest to the medical community.
Earlier probe architecture has sought to accommodate both the fragile nature and the piezoelectric reaction of cadmium-telluride-based crystal detectors with various forms of electrically conductive cushioning layers. Soft or yielding polymeric layers have been used where electrically insulative as well as electrically conductive properties have been called for. While a variety of these architectures have resulted in successfully performing probes, they have experienced manufacturing constraints. Additionally, the goal of evolving an advantageously heat sterilizable probe system has been an elusive one for investigators. However, probe mounted electronics have improved to the extent that some preamplifier circuits now will withstand the rigors of autoclaving. Further improvement has been called for in developing probe mounting structures which improve crystal detector performance but also which, of themselves, will withstand heat sterilization procedures.